As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to these users is an information handling system. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may vary with respect to the type of information handled; the methods for handling the information; the methods for processing, storing or communicating the information; the amount of information processed, stored, or communicated; and the speed and efficiency with which the information is processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include or comprise a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.
An information handling system may include a memory storage system or storage network that includes dual in-line memory modules, or “DIMMs.” A DIMM is a form of random-access-memory integrated circuit. Many information handling systems employ bi-directional, parallel channel designs for systems of DIMMs. Parallel channel DIMM systems, however, sometimes cannot provide the increased memory capacity required by increasingly fast new processors and improved input/output (“I/O”) subsystem performance. One cost-efficient solution to this problem may be serialized DIMM systems that include fully buffered DIMMs, or “FB-DIMMs.” FB-DIMM systems may be especially useful for high-end information handling systems, such as workstations and server platforms, to enable scaling of both bandwidth and density.
Although FB-DIMM systems allow for cost-efficient high-capacity memory systems, such systems may suffer an increased risk of system failure because the potential for multi-bit errors increases as memory capacity increases. As a result, FB-DIMM systems may utilize memory mirroring techniques, similar to a redundant array of independent disks (“RAID”), to guard against information loss in the case of a system failure. RAID storage systems combine multiple storage units into an array to obtain performance, capacity, and reliability advantages over other storage techniques, including, for example, using a single large storage device. In FB-DIMM systems using RAID storage techniques, multiple memory controllers simultaneously send read requests for information from a host through multiple channels of serialized FB-DIMMs that contain directly mirrored data. The host compares the data resulting from the requests to the different channels; inconsistencies between data read from the different channels indicate failures in the FB-DIMM system that should be investigated. Because the FB-DIMM system stores a directly mirrored set of the data, however, the likelihood that the data will be irretrievably lost in the case of a system failure is reduced.
Although such a directly mirrored FB-DIMM systems offer greater fault tolerance than non-mirrored systems, the availability of the directly mirror data set does not reduce read latencies caused by the serial architecture used with FB-DIMM systems. Read latencies result from “round-trip delays” that data requests experience as they travel through a channel: in a serial FB-DIMM system, the memory controllers must wait until the data request has traveled to each FB-DIMM in serial fashion and then return to the memory controller through each FB-DIMM, even if the requested information is available in the first FB-DIMM unit in the system. For directly mirrored FB-DIMM systems, a read request must travel to and from each FB-DIMM in the channel containing the original data, while substantially simultaneously traveling to and from each FB-DIMM in the channel containing the mirror data set. The resulting round-trip delays slow the operation of the FB-DIMM system.